by Marisol Bello and Natalie DiBlasio, USA TODAY

by Marisol Bello and Natalie DiBlasio, USA TODAY

Political extremists, criminals and gang members are advertising their wares, flaunting their exploits and recruiting new members in 140 characters or less, according to law enforcement authorities, criminologists and security experts.

The most shocking example occurred a week ago when the extremist group al-Shabab live-tweeted about the mall siege in Kenya, defending the mass killing, threatening more violence and taunting the military.

But the list is long - and growing - of those using Twitter and other social media venues for nefarious purposes.

Extremists spread their propaganda via video. Gangs post their colors, signs and rap songs to showcase their criminal enterprises. Prostitutes and drug dealers troll for new customers. Teens trash a former NFL player's house and brag about it with photos on Twitter.

But while Twitter can serve as a valuable recruitment and communications tool, it also can be a double-edged sword: Public boasting about illegal deeds can serve as a road map for law enforcement officials and lead to arrests.

Extremist groups, domestic and international, have been particularly savvy in their use of social media, says Evan Kohlmann, a senior partner with the security firm Flashpoint who specializes in the online communications of extremist groups. Twitter has become their site of choice because it is easy to sign up and remain anonymous among millions of users and tweets.

"These groups realize they need to reach as many people as possible," he says. "And Twitter and Facebook is where you find people."

In the beginning, extremist groups were reluctant to use social media. They relied on password-protected online forums, Kohlmann says. But as social sites became ubiquitous, the groups and their members jumped in like everyone else, he says.

One of the early and most prolific outfits to turn to Twitter was al-Shabab, the radical Somali group with links to al-Qaeda whose name means "The Youth" in Arabic.

Al-Shabab used Twitter during the hostage siege at the Westgate Shopping Mall in Nairobi to ballyhoo the mayhem blow-by-blow. Tweets defended the attack, mocked the Kenyan military and president, posted photos of members inside the mall and threatened more bloodshed.

Twitter shut down at least five different accounts used by al-Shabab. But each time the microblogging site suspended an account, the group created another with a different user name.

Twitter says it doesn't comment on individual accounts for security and privacy reasons.

Al-Shabab currently has a working feed on the site. Since Wednesday, the group posted audio statements by its leader, Ahmed Abdi Godane, also known as Mukhtar Abu Zubair, justifying the siege and threatening more attacks. It posted a tweet accusing the Kenyan government of demolishing the mall intentionally: "To cover their crime, the Kenyan govt carried out a demolition to the building, burying evidence and all hostages under the rubble #Westgate." The Associated Press reported Friday that the military caused the collapse, citing an unnamed senior Kenyan police official. The official said Kenyan troops fired rocket-propelled grenades inside the mall, but would not say what caused the collapse or whether it was intentional.

J.M. Berger, a security analyst who is editor of Intelwire, an online magazine that monitors extremist activity, says it's not the first time the group has tweeted about its activities in real time. He says Al-Shabab used Twitter to broadcast messages and threats during bombings in Mogadishu and to trumpet an attempt to assassinate the president of Somalia in early September.

"This time was more visible simply because the attack itself was more visible and unusual in its nature," Berger says.

NO GATEKEEPER ON HATE

A growing number of homegrown extremists are also turning to Twitter.

A May 2013 report on digital hate speech from the Simon Wiesenthal Center says Twitter helped spur a 30% growth in online forums for hate and terrorism over the past year. The study says more than 20,000 "hate-spewing hashtags and handles" appeared on Twitter in 2012, up 5,000 from the year before. The group identified Twitter as a "chief offender" among social media sites because of a lack of monitoring of hate and terrorist content.

Those who monitor extremist activity online say that as the site of choice for extremists, Twitter needs a clear, transparent policy as to what content is off-limits, and it has to enforce that policy vigorously.

"They respond to abuse reports, but their criteria for suspension is very limited," Berger said in an e-mail interview. He spotted al-Shabab's tweets during the mall siege and notified Twitter.

"They are broadly permissive of extremist content in a way that other services, like Facebook and YouTube, are not," he says.

Twitter, through spokesman Nu Wexler, would not make anyone from the company available for an interview. He directed a reporter to a blog post by the company's head of safety, Del Harvey, who wrote that manually reviewing every tweet is simply not possible. Users post up to 500 million tweets a day in more than 35 languages.

"We use both automated and manual systems to evaluate reports of users potentially violating our Twitter Rules," Harvey wrote. "These rules explicitly bar direct, specific threats of violence against others and use of our service for unlawful purposes, for which users may be suspended when reported.

INTERNET-BANGING AMPLIFIED

Closer to home, gangs in the United States have been adding Twitter and Facebook accounts to their arsenals for years in what University of Michigan social work professor Desmond Patton calls "Internet-banging."

"If we think about violence as a disease, one particular host of that disease is social media," he says.

Historically, displaying pictures of the gang or recording ''jump-ins,'' an initiation rite in which recruits endure a severe beating by gang members to demonstrate their toughness, or other acts of violence, required expensive equipment and lots of time, Patton says. That's no longer the case.

"With the advent of smartphone technology, youth can upload pictures and videos to social media sites quickly," he says.

A March study by Arizona State University criminologist Scott Decker found that nearly 20% of gang members reported that their gang had a website or social networking page and 50% said that their gang posts video online.

Eleven percent said their gang organized activities online, often using code. A gang member in St. Louis said he posted, "We got a baseball game" on Facebook to call the gang together for a fight. A gang member in Fresno said his gang avoided organizing drug business online but used the Internet to set up meetings, parties and even fundraisers for "bail or other emergencies."

Decker says gang members used to proclaim their allegiance via graffiti or by taunting their rivals.

"Now the kind of things that result in fighting take place online," he says. "Challenges to manhood, challenges to how tough the gang is. ... It could be YouTube videos, posting on someone's Facebook site."

He says gangs involved in drug dealing use Twitter, but because police know the corners and other spots where transactions generally take place, gang members will tweet out an address. He says the context of the tweet is unclear to a lay person, but the person on the receiving end understands the message.

DECIPHERING THE CODE

Rob D'Ovidio, a Drexel University criminologist, says gang members use code to boast about their deeds. For example, he says, they use "biscuit" or "clickety" for a gun, "food," "sea shells" or "gas" for bullets and "rock to sleep early" for murder.

He says street gangs are crafty in their online recruitment techniques. The gangs associate their group with popular music that has a violent message or a message that portrays ethnic oppression, which leads youngsters to believe they have something in common with the gang, he says.

"It is very reminiscent of how white supremacists use the World Wide Web to recruit kids," D'Ovidio says.

But the braggadocio can backfire.

In January 2012 in New York City, police arrested 43 gang members from rival gangs and linked them to six killings, 32 shootings, 36 robberies and numerous other crimes. The arrests came about because of posts the members put on Twitter crowing about what they had done.

Criminal activity online has led more than 2,600 police departments from New York City to Seattle to create social media units to monitor sites. Urban schools in Chicago monitor social media because fights that start online often spill into hallways.

Cincinnati police officer Dawn Keating was one of the first to track gangs on social media. In 2007, she began tracking a gang calling itself the Taliband that had a heavy presence on the now virtually forgotten MySpace. The gang posted photos of members, rap songs, its colors and signs. The posts helped Keating gather intel about the members and their connections. The online surveillance eventually led to 5,000 pieces of evidence and 90 indictments of gang members, she says.

She says drug dealers use Twitter to advertise their wares and their locations, and petty criminals brag about their exploits by posting photos of themselves with cash or stolen items on Facebook. She tells the story of a thief who committed five robberies in downtown Cincinnati. Police knew him only by a nickname, which they found on Facebook, along with photos of the man with cash and other items he'd stolen. That led to his arrest.

Prostitutes use Twitter to attract new customers or post their locations, daily specials and rates, the way lunch trucks let customers know where to find them, D'Ovidio says. He says they use hashtags such as #Vegas, #escort, #services and #callgirl.

"It clearly is a way for the call girl or prostitute to act as an individual entrepreneur in that it allows them to reach an audience for virtually no cost," D'Ovidio says. "In the past, they would need to hook up with an agency that would then advertise, via paid ads, at the back of free newspapers. Social media sites are allowing individuals to cut the middle person out."

And some bad actors do it just for the attention of a large audience that Twitter provides. Take the partying teens who broke into the vacation home of former NFL player Brian Holloway in Upstate New York, causing $20,000 in damage, including broken windows and holes in the wall. The teens posted photos of their antics on Twitter. Six people have been arrested so far and police expect dozens more arrests.

"With criminals, it's one thing to brag on the street," Cincinnati officer Keating says. "But now, with social media, they brag and get credibility worldwide."